You need to make sure that external DNS servers know to send mail to your server by IP.

Assuming your domain is "owned" by an ISP or hosting company, and that you are using a NAT router, you will need to put the external DNS of your network as an A record for a subdomain into their servers and also create an MX record pointing to that subdomain. Speak to support at your internet provider and they will probably talk you through it or do it for you.

e.g. a mail.xyz.com 123.123.123.123
mx xyz.com mail.xyz.com

Also you will need to open port 25 on your router to forward to the internal IP of your mail server.

I assume mail is bouncing, so I would send some test messages and check the headers to see where they fall down.

Quip doubles as a “living” wiki and a project management tool that evolves with your organization. As you finish projects in Quip, the work remains, easily accessible to all team members, new and old.
- Increase transparency
- Onboard new hires faster
- Access from mobile/offline

In this video we show how to create an Address List in Exchange 2013. We show this process by using the Exchange Admin Center.
Log into Exchange Admin Center.: First we need to log into the Exchange Admin Center.
Navigate to the Organization >> Ad…

To show how to generate a certificate request in Exchange 2013. We show this process by using the Exchange Admin Center.
Log into Exchange Admin Center.: First we need to log into the Exchange Admin Center.
Navigate to the Servers >> Certificates…